FMS Client freeze

I have a client app using the dynamic streaming classes provided by Adobe to play multiple bitrate live streaming video over RTMP. This is working really well for the most part but I find that occasionally (every 10 - 20 minutes) the buffer will empty and the video will freeze for 30-60 seconds. I'm running Adobe Scout and I can see that during the periods of frozen video the network events monitor is showing that the flash player is processing multiple events each frame. For example a sample frame might read '9 x Decoding media from network, 11 x receiving NetStream audio/video', whereas during periods when the video is playing normally there are typically only 1 or 2 of these events happening per frame. My theory is that the video is stalling because the entire frame is taken up processing these events but I have no idea why they are occurring multiple times or how to stop them. My buffertime is set to 2 seconds, I have 3 streams encoded at 250, 500 and 1300. The FMS is being served by Limelight and there is plenty of network capacity. If I run 2 client instances side by side one will continue playing while the other is stalled so I think this must be a client-side problem.

Any help greatly appreciated.